• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.58-64
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• 2008

In order to identify the exact behavior of corbel section, the horizontal force acting on corbel section should be considered as well as the vertical force. In this study, a new corbel section, which is economical and easy to construct, is developed by evaluating the exact strength of the section. Experiments were performed to verify the strengths of the proposed sections comparing with those of the currently used section. The summary of the experiment results are as follows: 1) In order to minimize the horizontal force effect, it was found that the use of pre-stressing was most effective, and that TB type corbel section is a most efficient section in terms of economy and workability. 2) The experimentally obtained strength of corbel section matched well with that estimated using shear friction theory. Therefore, it is concluded that shear friction theory would be very useful if a precise crack angie in the corbel section, which is pre-stressed by PS strings and threaded bolts, is available.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.61-73
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• 2002

Daegok dam is Concrete Face Rockfill Dam(C.F.R.D) of which 52m height, 190m length, that construction in beneath 306, Chanjeon-Ri, Dudong-Myeon, Ulju-Gun, Ulsan Metrocity. Left slope excavation of spillway have related to Daegok dam construction are developing crack in Sta. No. 1~2, EL. 134~137m after 67.0mm rainfall from 2000. 7. 23. 13:00 to 7. 24. 04:00. Surface geological survey and slope stability investigation with stereographic projection method in order of slope stability establishment. Partial supplement excavation and SSL. P. C. Anchoring method is able to pre-stressing are think about unstable element after excavation. This slope stability establishment is very successfully completion.

• Structural Engineering and Mechanics
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• v.38 no.2
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• pp.171-193
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• 2011

One of the possible alternatives of simulation-based time-dependent reliability assessment of pre-stressed biconcave and biconvex cable trusses, the Monte Carlo method, is applied in this paper. The influence of an excessive deflection of cable truss (caused by creep of cables and rheologic changes) on its time-dependent serviceability is investigated. Attention is given to the definition of the basic random variables and their statistical functions (basic, mutually dependent random variables such as the pre-stressing forces of the bottom and top cable, structural geometry, the Young's modulus of elasticity of the cables, and the independent variables, such as permanent load, wind, snow and thermal actions). Then, the determination of the response of the cable truss to the loading effects, and the definition of the limiting values considering serviceability of the structure are performed. The potential of the method, using direct Monte Carlo technique for simulation-based time-dependent reliability assessment as a powerful tool, is emphasized. Results obtained by the First order reliability method (FORM) are compared with those obtained by the Monte Carlo simulation technique.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.393-398
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• 2008

With the substantial increase of the size of structure, management and monitoring of excavation for the foundation construction becomes more difficult. Therefore, massive collapses which are related to retaining wall recently increase. However, since the study on measuring and monitoring the pre-stressing force of anchor is insufficient, behavior of anchor may not be predicted and monitored appropriately by the existing strain gauge type monitoring system. FBG Sensor, which is smaller than strain gauge and has better durability and does not have a noise from electromagnetic waves, was adapted to develope a smart anchor. A series of pullout tests were performed to verify the feasibility of smart anchor and find out the load transfer mechanism around the steel wire fixed to rock with grout.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.266-269
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• 2006

External pre-stressing strengthening method is the most popular way to strengthen concrete structures because of its efficiency and economic advantage. The laboratory test was performed to reinforce the slave bridge with the external tendon strengthening by longitudinally and transversally, which is concerned with formal feature of slave bridge, generally. Based on this test, anchoring device to strengthen the external tendon strengthening method was established and its strengthening effects were verified by evaluating the load bearing capacity.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.629-640
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• 2008

South anchorage(AN1, Myodo side) of supension bridge between Myodo and Gwangyang is designed as rock anchorage with 36m anchor length using the resistance of rock mass in Myodo. Checking the overall stability of the anchorage, we considered rock joints, bedding planes, fault zones and condition of rock structure in situ by analysis results for photo-lineaments, aerial photograph interpretation and drill-hole logs are considered. This anchorage consists of an access shaft, adit, and the upper and lower concrete bearing plate to introduce pre-stressing force into rock mass.

• Structural Engineering and Mechanics
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• v.43 no.1
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• pp.53-70
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• 2012

Sliding cable joints have been developed for the cable dome structures and the suspen-dome structures to reduce the cable pre-stressing loss and obtain a uniform inner force in each hoop cable. However, the relevant investigation is less addressed on the structural behavior of the cable dome structures and the suspen-dome structures with sliding cable joints due to the lack of analysis techniques. In this paper, a closed sliding polygonal cable element was established to analyze the structural behavior of the cable dome structures and the suspen-dome structures with sliding cable joints. The structural behaviors with sliding cable joints were obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.117-120
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• 2006

This study is for the strengthening method of continuous bridge through external tendon strengthening that is the most general and effective among concrete bridge's strengthening method. Recently, it is numerous that slab's parts between spans have continuity for improving trafficable ability. However, in this case, slab would have a crack; bridge's durability would be damaged, and also it is too difficult to manage and maintain bridge due to the tensile strength of negative moment. Therefore, the purpose of this study is to demonstrate load-carrying through experiments and develop new external pre-stressing strengthening method for reinforcing continuous bridge.

• Steel and Composite Structures
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• v.49 no.3
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• pp.281-291
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• 2023

Due to the fact that the nonlinear low-velocity impact response of graphene platelets reinforced metal foams (GPLRMF) doubly curved shells have not been investigated in the existing works, this paper aims to solve this issue. Using Reddy's high-order shear deformation theory (HSDT), the nonlinear governing equations of GPLRMF doubly curved shells are obtained by Euler-Lagrange method, discretized by Galerkin principle, and solved by the fourth-order Runge-Kutta method to obtain the impact force and central deflection. The nonlinear Hertz contact law is applied to determine the contact force. Finally, the impacts of graphene platelets (GPLs) distribution pattern, porosity distribution form, porosity coefficient, damping coefficient, impact parameters (radius and initial velocity), GPLs weight fraction, pre-stressing force and different shell types on the low-velocity impact curves are analyzed. It can be found that, among the four shell structures, the impact resistance of spherical shell is the best, while that of cylindrical shell is the worst.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.339-345
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• 2013

This study is to derive from the required performances and the optimum mix proportion of the roof concrete placed in the in-ground LNG storage tank with a capacity of 200000 $m^3$, and propose the actual data for site concrete work. The concrete placing work without sliding and segregation in the fresh concrete condition is very important because the slope of domed roof is varied in the large range by its curvature. Also the control of hydration heat and the strength development at test ages are classified with massive section about 1.4 m thick and considered to the pre-stressing work and removal of air support after concrete placing work. Considering above condition, slump range is selected $100{\pm}25$ mm under the slope $20^{\circ}$ and $150{\pm}25$ mm over the slope $20^{\circ}$ s until 60 minutes of elapsed time. Also, the roof concrete is satisfied with compressive strength range including design strength at 91 days (30 MPa), pre-stressing work at 7 days (10 MPa), air support removal work at 21 days (14 MPa). Replacement ratio of limestone powder is determined by confined water ratio test and main design factors include water-cement ratio (W/C), sand-aggregate ratio and dosage of admixture. As test results, the optimum mix proportion of the roof concrete used low heat cement is as followings. 1) Replacement ratio of limestone powder 25% by confined water ratio test 2) Water-cement ratio 57.8% 3) Sand-aggregate ratio 42.0%. Also, test results for the adiabatic temperature rising test is satisfied with its criteria and shown the lower value compared to preceding storage tank (TK-13, 14). These required performances and the optimum mix proportion is to apply the actual construction work.